Regulator for compound engines



(No Model.) 2 Sheets-Sheet 1.

C. T. MAIN.

REGULATOR FOR COMPOUND ENGINES.

No. 397,507. Patented Pebflz, 1889.

GIIIIIIlIE Wines s 65 N. PIJERS. Phololiihoghpher. Wnhinqm. D.C.'

(No Model.) 2 Sheets-Sheet 2.

C. T. MAIN.

REGULATOR FOR COMPOUND ENGINES.

No. 397,507. Patented Feb. 12, 1889.

H x M 70 m V. k

Witnesses, j'nvafiiary Charles. I fife tin, 3 wzmnc um- 44%, I 1

N. PETERS. Phclu-Ulhognpbar. Wnhinglcn. ac.

NITED STATES rricn,

PATENT CHARLES MAIN, OF LA\VRENCE, MASSACHUSETTS.

SPECIFICATION forming part of Letters Patent No. 397,507, dated February 12, 1889.

Application filed uly 5, 1888. Serial No, 279,056. (No model.)

To all whom it 77mg concern:

Be it known that I, CHARLES TxMam, of Lawrence, county of Essex, and State of Massachusetts, have invented an In'iprovement in Regulators for Receiver-Pressure of Compound Engines, of which the following description, in connection with the accompanying drawings,is a specification, like letters on the drawings representing like parts.

In many manut'actu ring establishments employing a compound engine for actuating machinery steam is taken from the receiver that conveys the exhaust from the high-pressure engine to the low-pressure engine for various purposes requiring steam at a comparatively low pressure, and the amount of steam thus drawn from the receiver at different times is variable, and thus gives rise to variations in pressure in the receiver, and consequently in the lmv-pressure engine when the latter runs with constant cut-off. For this reason it is customary in establishments where steam is taken from the receiver of a compound engine for other purposes than for actuating the low-pressure engine to change the cut-off of the low-pressure enginefrom time to time by hand, so as to keep the pressure in the receiver as nearly constant as possible; but this method of operation is not satisfactory, as it requires constant watchfulness on the part of the attendant to observe the variations in the receiver-pressure, and the proper changes in the cut-off of the low-pressure engine are not always made promptly.

The object of the present invention is to provide means for automatically varying the cut-off in thelow-pressure engine as the press ure in the receiver varies owin g to variations in the consumption of steam from the receiver, for other purposes than driving the engine, said regulator shortening the cut-off when the pressure falls, owing to a large external conslunption, and lengthening the cut off when the pressure rises, owing to a 001m paratively small external consumption, and thus tending to keep the pressure nearly uniform in the receiver, and, in fact, preventing it from varying in either direction beyond certain narrow predetermined limits.

Figure 1 is an elevation of a regulator for the receiver-pressure of a compound engine embodying this invention, showing also a sufficient portion of the engine to illustrate the relation of the regulator thereto; and Fig. 2 is a side elevation on a plane at right angles to that of Fig. 1, of the regulator, showing also a sufficient portion of the valve-gear of the low-pressure engine to illustrate the mode of operation of said regulator.

The invention is applicable to any usual type of compound engine comprisii'ig a highpressure engine, the cylinder of which is shown at a, Fig. 1, and receives the steam from the steam-generator through the pipe I), and exhausts the steaminto the pipe c, which conveys a greater or less portion of the steam thus exhausted from thehigh-pressure engine to the cylinder (Z of the low-pressure engine, from which the steam is exhausted bya pipe, 6, into a condenser, which is not shown, as it forms no part of this invention.

The pipe 0 constitutes the receiver of the compound engine and may be extended to various points in the mill or manufactory, so as to supply the steam required for various purposes, for which steam at a comparatively low pressure can be economically used, it being understood that the amount of steam delivered into the receiver from the high-pressure engine is always somewhat in excess of the amount required for consumption outside of the engine. As the amounts drawn for such outside consumption vary widely at different times in the running of the mill, there would be corresponding variations in the pressure in the receiver if the amount taken by the low-pressure engine remained substantially constant, and such variations would be only partially compensated for, if at all, by the usual speed-regulator of the engine.

It is desirable to maintain the pressure in the receiver as nearly constant as possible, and this is effected automatically, in accordance with this invention, by means of a regulating device that varies the cut-off in the lowpressure engine in accordance with. changes in pressure in the receiver, lengthening the cut-off as the pressure tends to rise, and thus consuming a larger portion of steam from the receiver in the low pressure engine, and shortening the cut-off as the pressure falls, and thus using a smaller amount of steam in the IOO low-pressure engine when a large amount is withdrawn for external purposes.

This regulator, as shown in this instance, consists of a cylinderf, containing a piston, f, and communieatiug above the said piston with the receiver 0, as by the pipe f so that the upper side of the piston is exposed to the pressure in the receiver while the under side is exposed only to an atmospheric pressure, the lower part of the cylinder being open to the atmosphere through the pipe or outlet The piston f" is connected by a rod, h, and pitman h with a cut-off-eontrolling lever, 1, (best shown in Fig. 2,) that controls the cuts off valves of the low-pressure engine, which valves may be of any usual kind, being shown in this instance as of the well-known Corliss type, which. will be briefly described hereinafter, it being sufficient for the present to understand that raising the rod hand lever t shortens the cut-off of the low-pressure engine. The rod 71 is connected at 7L2 with one arm of a three-armed lever, 7.", pivoted atlr. on a suitable bracket or support, two arms of which lever in the operation of the lever rise and fall a short distance above and below the horizontal position, while the third inclines more or less from the vertical position. The horizontal arm of the lever It is provided with a weight, m, and the vertical arm with a weight, 'n, which operates as follows: lVheu the pressure is at the lowest admissible point in the receiver, the cut-off in the low-pressure cylinder must be the shortest, and the piston f" is at its highest position. The weight 12 is then vertically below the point 7.1 of the lever 7;, and has no leverage and consequently no effect on the piston, and the weight in, which is then slightly below the horizontal position, is adjusted to justbalance the minimum pressure on the piston and other parts connected therewith and the frictional resistance to their moven'ient. The said cylinder f constitutes a pressure-ehamber, and the piston is a part moved by variations in the pressure in said chamber, being arranged to respond to slight changes in said pressure, and constituting, as it were, a pressure-gage that responds to variations in pressure in the engine-receiver, and it is obvious that any of the well-known pressure gages or contrivances having a part. correspomling to the piston j" that moves in one or the other direction, according as the pressure rises or falls, might be substituted as a mechanical equivalent for the piston and cylinder, which. latter constitute, however, a very efficient and convenient gagefor the regulator forming the subject;- of this invention. Then as the pressure in the receiver increases it tends to force the piston f" downward and to move the weight n from the position vertically below the point so that the said weight acts with gradually-increasing leverage until, when the piston f arrives at the lowest point, the said weight n exerts sufficient force to balance the increase in pressure in the receiver, which is then at the highest point allowable, the amount of variation between the maximum and minimum pressure of the steam in the receiver being determined by the amount of the weight n, which can be chosen to keep the variation within any required limits.

It is obvious that a spring might be employed instead of the weightnas indicated, for example, in dotted lines at -nin order to produce a variable resistance to the movement of the piston f.

\Vhen used in connection with the Corliss cut-oft, as shown in this instance, the lever is pivoted at i upon an arm of the governorpedcstal 0, and is provided with a roller, 2 that bears against the lower edge of the governorsleeve 0, which is provided with a groove engaging a projection or roller on one arm of a three-armed lever, p, the other two arms of which are connected by links 0* and r with the tripping device for the valves at each end of the cylinder, one only of said valves being shown, as it is sul'istantially the same in construction as the other.

The valves are actuated by the usual w ristplate or rocker, '1, which is oscillated at each revolution of the engine and is provided with wrist-pins 1, connected by links f with rocking levers '21, pivoted at u concentrically with the spindle of the valve that admits steam to the engine. The said valve-spindle has connected with it an arm, 1', which is engaged by a catch, r, pivoted on the rocking lever 11 which causes the arm r and valve to accompany the said rocking lever u in a greater or less portion of its movement, as determined by the tripping device 11', which eo-operates with a projection on the catch 1", and is connected at one end with the link r, and also with a radius-bar, "zr, pivoted at 'u' upon the frame-work. \Vhen the lever is raised, the tripping device disengages the catch from the lever-arm r earlier in the movement of the rocking-lever u, and thus cuts o'lt' the admis sion of steam to the cylinder earlier than when the said lever '1' is in the lower position.

The governor o of the low-pressure cylinder should be set to have no effect upon the cut off, due to slight changes in speed from the normal speed of the engine, although it will act after a slight percentage of increase in speed to diminish the cut-oil", and thus prevent great acceleration of the engine in case its lead should he suddenly reduced.

The governor on the high-pressure engine operates with variations in speed and thus regulates the engine in the usual manner.

The operation of the entire apparatus is substantially as follows: \Yhen a very large amount of steam is used from the receiver for external purposes, the piston f rises and shortens the cut-off of the lowpressure engine, so that the latter takes but comparatively little steam from the receiver, and the pressure therein is not diminished below the predetermined minimum amount. The lowpressure engine then does a smaller portion IIO of the work, and if the speed of the engine tends to fall off in consequence the regulator of the high-pressure engine will admit more steam thereto, thus tending toexhaust more steam into the receiver and prevent the pressure from falling below such predetermined minimum limit. ll, on the other hand, the amount of steam consumed for external purposes is diminished, the pressure in the receiver rises and forces down the piston f and lengthens the cut-off of the low-pressure engine, so that a larger amount of steam is used from the rcceiverfor power, and if the greater power leveloped by the low-pressure engine tends to increase the speed the regulator ot' the high-pressure engine will diminish the amount of steam supplied thereto, and consequently the engine will be kept running with nearly uniform pressrnre in the receiver, thus giving practically uniform pressure of the steam admitted to the low-pressure engine and insuring uniformity of back-pressure in the high-pressure cylinder-conditions which are most favorable for the economical working of the engine. There is no waste of steam from the receiver through a relief or safety valve, as is the case when the low-pressure engine runswith constant cut-oft, when it may happen that a considerable diminution in the quantity of steam drawn. from the receiver to r external uses increases the pressure in the receiver, for while such increase in pressure might tend to make the low-pressure engine do more work, the increase in back-pressure would make the high-pressure engine do less work, so that the speed of the engine might not increase, and consequently the amount of steam admitted to the high-pressure engine wvould not be diminished by the speed-govexternal purposes when the exhaust for the,

higlrpressure engine is not sufficient.

The herein-described regulating device prevents the operation of said valve until the cut-oft in tl1el( wi1'essu1'e cylinder reaches the shortest admissible point and the cutoff of thehigh-pressure cylinderreaches itsmaximum length, owing to thediminution in work done by the low-pressure engine, so that the largest possible amount of steam passes through the high-pressure cylinder and performs its work therein; and no steam is allowed to pass through the reducing-valve and expand without doing work until the draft of steam for exteriiial purposes is greater than the engine can possibly supply.

1. A regulator for compound engines, com prising a pressure-gage or pressure-chauil)er connected with the receiver and havin a part movable by changes in the pressure in said receiver, the said moving part of the pressure gage h ein g conn ected with the cut-off controller for the valves of the low-pressure engine, and by its movement changing the cut-oft for said valves, as set forth, whereby the quantity of steam admitted to the low-pressure engine from the receiver is increased as the pressure in the receiver rises and is diminished. as the pressure in the receiver falls, substantially as and for the purpose described.

2. A regulator for compound engines, comprising a cylinder and piston therein, said cylinder communicating with the receiver of the engine, and said piston being connected with the cut-off controller of the low-pressure engine combined with a weighted lever connected with said piston, having one weighted arm which moves a short distance above and below the horizontal. position, and a second weighted arm that moves toward and from the vertical position in the stroke of said piston, substantially as and for the purpose dcscri bed.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

CHAS. T. MAIN.

lVitnesses:

FRANZ II. SCIUYARZ, W. W. LATI-iROP. 

